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Ahmed Abdelwahab - One of the best experts on this subject based on the ideXlab platform.
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removal of se iv by the dithionite ultraviolet advanced Reduction Process effects of Process variables
Environmental Engineering Science, 2018Co-Authors: Bahngmi Jung, Bill Batchelor, Ahmed Abdelwahab, Aya Safan, Yuhang Duan, Vishakha KaushikAbstract:Abstract This study investigates removal of selenite [Se(IV)] by reductive precipitation during treatment with an Advanced Reduction Process (ARP) that uses dithionite activated by ultraviolet (UV)...
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chlorate Reduction by dithionite uv advanced Reduction Process
International Journal of Environmental Science and Technology, 2017Co-Authors: Bahngmi Jung, Bill Batchelor, Ahmed Abdelwahab, R SivasubramanianAbstract:Chlorate is one of the disinfection byproducts that are formed when chlorine/chlorine dioxide is used as a primary disinfectant. This study investigated the removal of chlorate by photochemical degradation using an advanced Reduction Process, which is a treatment method that combines a reducing agent with an activating method to generate reducing radicals. The effectiveness of combinations of reducing agents and three UV light sources having a peak output at 254, 365, and 312 nm were evaluated for chlorate removal. Dithionite irradiated by broad-band UVB lamp having the peak energy at 312 nm showed the highest chlorate removal. In pursuit of finding the optimum advanced Reduction Process conditions, the environmental Process variables including pH, reducing agent dose, and light intensity were investigated. Dithionite/UV-B advanced Reduction Process was effective in weakly acidic conditions (pH < 5), and chlorate removal occurred in two steps. The first was an initial rapid decrease in chlorate concentration that occurred before initiating UV irradiation and was attributed to reaction with dithionite decomposition products. The second step was a slow decrease during UV irradiation that is caused by radicals produced by photolysis of the products of dithionite decomposition. The major product of chlorate destruction was chloride, with negligible amounts of chlorite produced.
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application of uv sulfite advanced Reduction Process to bromate removal
Journal of water process engineering, 2015Co-Authors: Venkata S V Botlaguduru, Bill Batchelor, Ahmed AbdelwahabAbstract:Abstract Bromate is a possible human carcinogen regulated in drinking water at a maximum contaminant level (MCL) of 10 μg/L. This research applied an advanced Reduction Process (ARP) that combined sulfite (SO 3 2− ) as a reducing agent and UV as the activating method to remove bromate. In addition to photolysis, this UV–sulfite ARP generates sulfite anion radicals (SO 3 − ) and aqueous electrons (e aq − ) that react with and reduce the target bromate. Results from batch experiments showed pseudo first-order removal of bromate with rate constants ( K obs ) varying from 0.015 to 2.11 min −1 . The effect of Process variables like sulfite dose, pH and UV characteristics on the kinetics were studied. The Reduction kinetics improved with increasing sulfite doses and UV intensities. Acidic pH resulted in decreased kinetics, with pH above 7, resulting in the highest observed rate constants. Two different UV wavelengths, 222 nm and 254 nm were used to activate sulfite in solution. Lower wavelength UV resulted in kinetics two orders of magnitude higher than UV at 254 nm. Quantum yields for this ARP were calculated to be in the range of 0.016–0.036 mol/Einstein. The principal Reduction end products were bromide and sulfate, with recovery of bromide ranging from 80% to 90%. The overall results indicate a promising application potential for ARPs in the removal of disinfection byproducts in water.
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degradation of vinyl chloride vc by the sulfite uv advanced Reduction Process arp effects of Process variables and a kinetic model
Science of The Total Environment, 2013Co-Authors: Xu Liu, Sunhee Yoon, Bill Batchelor, Ahmed AbdelwahabAbstract:Abstract Vinyl chloride (VC) poses a threat to humans and environment due to its toxicity and carcinogenicity. In this study, an advanced Reduction Process (ARP) that combines sulfite with UV light was developed to destroy VC. The degradation of VC followed pseudo-first-order decay kinetics and the effects of several experimental factors on the degradation rate constant were investigated. The largest rate constant was observed at pH 9, but complete dechlorination was obtained at pH 11. Higher sulfite dose and light intensity were found to increase the rate constant linearly. The rate constant had a little drop when the initial VC concentration was below 1.5 mg/L and then was approximately constant between 1.5 mg/L and 3.1 mg/L. A degradation mechanism was proposed to describe reactions between VC and the reactive species that were produced by the photolysis of sulfite. A kinetic model that described major reactions in the system was developed and was able to explain the dependence of the rate constant on the experimental factors examined. This study may provide a new treatment technology for the removal of a variety of halogenated contaminants.
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photochemical degradation of vinyl chloride with an advanced Reduction Process arp effects of reagents and ph
Chemical Engineering Journal, 2013Co-Authors: Xu Liu, Sunhee Yoon, Bill Batchelor, Ahmed AbdelwahabAbstract:Abstract A new treatment technology, called an Advanced Reduction Process (ARP), was developed by combining UV irradiation with reducing reagents to produce highly reactive reducing free radicals that degrade contaminants. Batch experiments were performed under anaerobic conditions to investigate the degradation of vinyl chloride (VC) by this ARP. All degradation reactions were found to follow a pseudo-first-order decay model and the rate constants (kobs) were characterized for all experimental conditions. The influence of pH on kobs was studied in experiments with direct photolysis as well as experiments with ARPs using reagents activated by ultraviolet (UV) light. Values for kobs in direct photolysis were found to be 0.012, 0.011, and 0.018 min−1 at pH 3, 7 and 10, respectively. Values of most of the kobs in experiments with ARP increased at all pH values compared with corresponding values obtained for direct photolysis. The increase in kobs was due to the production of reactive species produced by photochemical reaction of the reducing reagents with UV light. The pH effect on kobs observed with the ARP can be explained in terms of changes in the absorption spectra of the reagents at various pH. The rate of light absorption determines the rate of formation of the reactive species which determines the rate of contaminant degradation. Chloride ion and chloroethane were detected as the products of VC degradation. The increase in pH value was shown to promote the transformation of VC to chloride.
Janine Cossy - One of the best experts on this subject based on the ideXlab platform.
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synthesis of omega hydroxy ketones from omega benzyloxy weinreb amides by using a chemoselective nucleophilic addition birch Reduction Process
Organic Letters, 2004Co-Authors: Catherine Taillier, Veronique Bellosta, Christophe Meyer, Janine CossyAbstract:A chemoselective nucleophilic addition/Birch Reduction Process applied to ω-benzyloxy Weinreb amides led to ω-hydroxy ketones in good yields.
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synthesis of omega hydroxy ketones from omega benzyloxy weinreb amides by using a chemoselective nucleophilic addition birch Reduction Process
Organic Letters, 2004Co-Authors: Catherine Taillier, Veronique Bellosta, Christophe Meyer, Janine CossyAbstract:[reaction: see text] A chemoselective nucleophilic addition/Birch Reduction Process applied to omega-benzyloxy Weinreb amides led to omega-hydroxy ketones in good yields.
Catherine Taillier - One of the best experts on this subject based on the ideXlab platform.
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synthesis of omega hydroxy ketones from omega benzyloxy weinreb amides by using a chemoselective nucleophilic addition birch Reduction Process
Organic Letters, 2004Co-Authors: Catherine Taillier, Veronique Bellosta, Christophe Meyer, Janine CossyAbstract:A chemoselective nucleophilic addition/Birch Reduction Process applied to ω-benzyloxy Weinreb amides led to ω-hydroxy ketones in good yields.
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synthesis of omega hydroxy ketones from omega benzyloxy weinreb amides by using a chemoselective nucleophilic addition birch Reduction Process
Organic Letters, 2004Co-Authors: Catherine Taillier, Veronique Bellosta, Christophe Meyer, Janine CossyAbstract:[reaction: see text] A chemoselective nucleophilic addition/Birch Reduction Process applied to omega-benzyloxy Weinreb amides led to omega-hydroxy ketones in good yields.
Bill Batchelor - One of the best experts on this subject based on the ideXlab platform.
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removal of se iv by the dithionite ultraviolet advanced Reduction Process effects of Process variables
Environmental Engineering Science, 2018Co-Authors: Bahngmi Jung, Bill Batchelor, Ahmed Abdelwahab, Aya Safan, Yuhang Duan, Vishakha KaushikAbstract:Abstract This study investigates removal of selenite [Se(IV)] by reductive precipitation during treatment with an Advanced Reduction Process (ARP) that uses dithionite activated by ultraviolet (UV)...
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chlorate Reduction by dithionite uv advanced Reduction Process
International Journal of Environmental Science and Technology, 2017Co-Authors: Bahngmi Jung, Bill Batchelor, Ahmed Abdelwahab, R SivasubramanianAbstract:Chlorate is one of the disinfection byproducts that are formed when chlorine/chlorine dioxide is used as a primary disinfectant. This study investigated the removal of chlorate by photochemical degradation using an advanced Reduction Process, which is a treatment method that combines a reducing agent with an activating method to generate reducing radicals. The effectiveness of combinations of reducing agents and three UV light sources having a peak output at 254, 365, and 312 nm were evaluated for chlorate removal. Dithionite irradiated by broad-band UVB lamp having the peak energy at 312 nm showed the highest chlorate removal. In pursuit of finding the optimum advanced Reduction Process conditions, the environmental Process variables including pH, reducing agent dose, and light intensity were investigated. Dithionite/UV-B advanced Reduction Process was effective in weakly acidic conditions (pH < 5), and chlorate removal occurred in two steps. The first was an initial rapid decrease in chlorate concentration that occurred before initiating UV irradiation and was attributed to reaction with dithionite decomposition products. The second step was a slow decrease during UV irradiation that is caused by radicals produced by photolysis of the products of dithionite decomposition. The major product of chlorate destruction was chloride, with negligible amounts of chlorite produced.
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application of uv sulfite advanced Reduction Process to bromate removal
Journal of water process engineering, 2015Co-Authors: Venkata S V Botlaguduru, Bill Batchelor, Ahmed AbdelwahabAbstract:Abstract Bromate is a possible human carcinogen regulated in drinking water at a maximum contaminant level (MCL) of 10 μg/L. This research applied an advanced Reduction Process (ARP) that combined sulfite (SO 3 2− ) as a reducing agent and UV as the activating method to remove bromate. In addition to photolysis, this UV–sulfite ARP generates sulfite anion radicals (SO 3 − ) and aqueous electrons (e aq − ) that react with and reduce the target bromate. Results from batch experiments showed pseudo first-order removal of bromate with rate constants ( K obs ) varying from 0.015 to 2.11 min −1 . The effect of Process variables like sulfite dose, pH and UV characteristics on the kinetics were studied. The Reduction kinetics improved with increasing sulfite doses and UV intensities. Acidic pH resulted in decreased kinetics, with pH above 7, resulting in the highest observed rate constants. Two different UV wavelengths, 222 nm and 254 nm were used to activate sulfite in solution. Lower wavelength UV resulted in kinetics two orders of magnitude higher than UV at 254 nm. Quantum yields for this ARP were calculated to be in the range of 0.016–0.036 mol/Einstein. The principal Reduction end products were bromide and sulfate, with recovery of bromide ranging from 80% to 90%. The overall results indicate a promising application potential for ARPs in the removal of disinfection byproducts in water.
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perchlorate Reduction by the sulfite ultraviolet light advanced Reduction Process
Journal of Hazardous Materials, 2013Co-Authors: Bhanu Prakash Vellanki, Bill BatchelorAbstract:Advanced Reduction Processes (ARPs) are a new class of water treatment Processes that combine activation methods and reducing agents to form highly reactive reducing radicals that degrade oxidized contaminants. The combination of sulfite with low-pressure ultraviolet light (UV-L) is the most effective ARP tested to date. In this study, batch kinetic experiments were conducted to characterize the kinetics of perchlorate destruction by the sulfite/UV-L ARP. Experimental variables were pH, sulfite concentration, temperature and UV-L irradiance. The rate of perchlorate degradation by sulfite/UV-L increases with increasing pH and temperature and increases with increasing sulfite concentration to a maximum and then decreases due to lack of mixing within the reactor system used. Efficiency of perchlorate degradation was measured as a quantum yield and was observed to decrease with increasing sulfite concentration. The ultimate product of perchlorate degradation by the sulfite/UV-L ARP is chloride, but chlorate was detected as an intermediate.
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degradation of vinyl chloride vc by the sulfite uv advanced Reduction Process arp effects of Process variables and a kinetic model
Science of The Total Environment, 2013Co-Authors: Xu Liu, Sunhee Yoon, Bill Batchelor, Ahmed AbdelwahabAbstract:Abstract Vinyl chloride (VC) poses a threat to humans and environment due to its toxicity and carcinogenicity. In this study, an advanced Reduction Process (ARP) that combines sulfite with UV light was developed to destroy VC. The degradation of VC followed pseudo-first-order decay kinetics and the effects of several experimental factors on the degradation rate constant were investigated. The largest rate constant was observed at pH 9, but complete dechlorination was obtained at pH 11. Higher sulfite dose and light intensity were found to increase the rate constant linearly. The rate constant had a little drop when the initial VC concentration was below 1.5 mg/L and then was approximately constant between 1.5 mg/L and 3.1 mg/L. A degradation mechanism was proposed to describe reactions between VC and the reactive species that were produced by the photolysis of sulfite. A kinetic model that described major reactions in the system was developed and was able to explain the dependence of the rate constant on the experimental factors examined. This study may provide a new treatment technology for the removal of a variety of halogenated contaminants.
Zengqiang Zhang - One of the best experts on this subject based on the ideXlab platform.
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preparation of a carbon based solid acid catalyst by sulfonating activated carbon in a chemical Reduction Process
Molecules, 2010Co-Authors: Miao Huang, Zengqiang ZhangAbstract:Sulfonated (SO3H-bearing) activated carbon (AC-SO3H) was synthesized by an aryl diazonium salt Reduction Process. The obtained material had a SO3H density of 0.64 mmol·g-1 and a specific surface area of 602 m2·g-1. The catalytic properties of AC-SO3H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO3H (78%) was lower than that of Amberlyst-15 (86%), which could be attributed to the fact that the SO3H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g-1). However, AC-SO3H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO3H is the leaching of SO3H group during the reactions.
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preparation of a carbon based solid acid catalyst by sulfonating activated carbon in a chemical Reduction Process
Molecules, 2010Co-Authors: Xiaoyan Liu, Yulei Zhu, Miao Huang, Zengqiang Zhang, Jinming Gao, Xiaojin Han, Xiangyun GuoAbstract:Abstract: Sulfonated (SO 3 H-bearing) activated carbon (AC-SO 3 H) was synthesized by an aryl diazonium salt Reduction Process. The obtained material had a SO 3 H density of 0.64 mmol·g -1 and a specific surface area of 602 m 2 ·g -1 . The catalytic properties of AC-SO 3 H were compared with that of two commercial solid acid catalysts, Nafion NR50 and Amberlyst-15. In a 10-h esterification reaction of acetic acid with ethanol, the acid conversion with AC-SO 3 H (78%) was lower than that of Amberlyst-15 (86%), which could be attributed to the fact that the SO 3 H density of the sulfonated carbon was lower than that of Amberlyst-15 (4.60 mmol·g -1 ). However, AC-SO 3 H exhibited comparable and even much higher catalytic activities than the commercial catalysts in the esterification of aliphatic acids with longer carbon chains such as hexanoic acid and decanoic acid, which may be due to the large specific surface area and mesoporous structures of the activated carbon. The disadvantage of AC-SO
